capture stdout and display in dialog window

tools/lammps-gui/stdcapture.cpp

@@ -0,0 +1,119 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://www.lammps.org/, Sandia National Laboratories
+   LAMMPS development team: developers@lammps.org
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+   ------------------------------------------------------------------------- */
+
+// adapted from: https://stackoverflow.com/questions/5419356/redirect-stdout-stderr-to-a-string
+
+#include "stdcapture.h"
+
+#ifdef _MSC_VER
+#include <io.h>
+#define popen _popen
+#define pclose _pclose
+#define stat _stat
+#define dup _dup
+#define dup2 _dup2
+#define fileno _fileno
+#define close _close
+#define pipe _pipe
+#define read _read
+#define eof _eof
+#else
+#include <unistd.h>
+#endif
+
+#include <chrono>
+#include <cstdio>
+#include <fcntl.h>
+#include <thread>
+
+StdCapture::StdCapture() : m_capturing(false), m_oldStdOut(0)
+{
+    // make stdout unbuffered so that we don't need to flush the stream
+    setvbuf(stdout, NULL, _IONBF, 0);
+
+    m_pipe[READ]  = 0;
+    m_pipe[WRITE] = 0;
+#if _MSC_VER
+    if (pipe(m_pipe, 65536, O_BINARY) == -1) return;
+#else
+    if (pipe(m_pipe) == -1) return;
+#endif
+    m_oldStdOut = dup(fileno(stdout));
+    if (m_oldStdOut == -1) return;
+}
+
+StdCapture::~StdCapture()
+{
+    if (m_capturing) {
+        EndCapture();
+    }
+    if (m_oldStdOut > 0) close(m_oldStdOut);
+    if (m_pipe[READ] > 0) close(m_pipe[READ]);
+    if (m_pipe[WRITE] > 0) close(m_pipe[WRITE]);
+}
+
+void StdCapture::BeginCapture()
+{
+    if (m_capturing) EndCapture();
+    dup2(m_pipe[WRITE], fileno(stdout));
+    m_capturing = true;
+}
+
+bool StdCapture::EndCapture()
+{
+    if (!m_capturing) return false;
+    dup2(m_oldStdOut, fileno(stdout));
+    m_captured.clear();
+
+    constexpr int bufSize = 1025;
+    char buf[bufSize];
+    int bytesRead;
+    bool fd_blocked;
+
+    do {
+        bytesRead  = 0;
+        fd_blocked = false;
+
+#ifdef _MSC_VER
+        if (!eof(m_pipe[READ])) {
+            bytesRead = read(m_pipe[READ], buf, bufSize - 1);
+        }
+#else
+        bytesRead = read(m_pipe[READ], buf, bufSize - 1);
+#endif
+        if (bytesRead > 0) {
+            buf[bytesRead] = 0;
+            m_captured += buf;
+        } else if (bytesRead < 0) {
+            fd_blocked = ((errno == EAGAIN) || (errno == EWOULDBLOCK) || (errno == EINTR));
+
+            if (fd_blocked) std::this_thread::sleep_for(std::chrono::milliseconds(10));
+        }
+    } while (fd_blocked || (bytesRead == (bufSize - 1)));
+    m_capturing = false;
+    return true;
+}
+
+std::string StdCapture::GetCapture() const
+{
+    std::string::size_type idx = m_captured.find_last_not_of("\r\n");
+    if (idx == std::string::npos) {
+        return m_captured;
+    } else {
+        return m_captured.substr(0, idx + 1);
+    }
+}
+
+// Local Variables:
+// c-basic-offset: 4
+// End: